1. Field of the Invention
This invention relates to fiber optics with particular reference to improvements in line illuminators for document copiers.
2. Discussion of the Prior Art
Many document copiers utilize an optical system which scans a line of information over the length (or width) of the document. The thickness of this line may vary from a few to several millimeters.
To obtain maximum efficiency, a means for illuminating only the "line" area of a document is desirable and one method of doing this is to use a fiber optic "fan". This comprises a bundle of optical fibers having their light-output ends juxtapositioned along a line and opposite input ends tightly bundled, e.g. into a circular array which may be illuminated with a tungsten halogen lamp.
A problem with this method has been that irregularities, fiber breakage or gaps in the strip end of the fiber optic fan will cause non-uniform illumination and give rise to streaks on the copy. This can be at least partially overcome by moving the fiber bundle away from the document to "blend" the light, but not without a substantial loss of illumination level.
It is, accordingly, a principal object of this invention to provide both uniformity of illumination and high level illumination in line-scanning systems.
Another object is to accomplish the foregoing simply and economically and further in a manner having compatibility with requirements of various forms of line-scanning document copying systems.
Other objects and advantages of the invention will become more readily apparent from the following description.